Bird cage



FIG. 1 is a front perspective view of a bird cage showing my new design;

FIG. 2 is a front elevational view thereof showing the doors in open position;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side elevational view thereof, the left side being a mirror image of the right side shown; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a bird cage, as shown and described. 